The present invention relates to a backrest adjustment device. More particularly, the present invention relates to a backrest adjustment device which adjusts a backrest of a chair easily.
A conventional backrest adjustment device has a complex structure. It is difficult for a user to operate the conventional backrest adjustment device.
An object of the present invention is to provide a backrest adjustment device which adjusts an angle of a backrest of a chair easily.
Accordingly, a backrest adjustment device comprises a hollow base seat, an oblong panel, a guide mount, a slide seat, a nut, a coiled spring, a compression spring, a positioning plate, a top panel, a screw rod, and a control rod. The positioning plate has a threaded aperture. The oblong panel has a threaded hole. The guide mount is disposed on the oblong panel. The guide mount has a bottom recess and an oblong hole. The positioning plate is inserted in the bottom recess of the oblong panel. The slide seat has a bottom groove, a slant slot, and a lateral lug. The screw rod has a disk head. The top panel has a plurality of click serrations. The top panel engages with the hollow base seat. The control rod has an oval plate, an extension bar, and a plurality of annular grooves. The screw rod passes through the compression spring, the lateral lug, the coiled spring, the nut, and the oval plate. The extension bar is disposed between the top panel and the hollow base seat. A screw passes through the slot of the slide seat, the oblong hole of the guide mount, and the threaded aperture of the positioning plate.